039  
FXUS61 KBOX 080154  
AFDBOX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BOSTON/NORTON MA  
954 PM EDT TUE MAY 7 2024  
   
SYNOPSIS
 
 
A WARM FRONT WILL BRING A ROUND OF SHOWERS AND ISOLATED  
THUNDERSTORMS VERY LATE TONIGHT AND WEDNESDAY. CHANCES FOR A FEW  
STRONG THUNDERSTORMS CAPABLE OF PRODUCING HAIL IN WESTERN MA/CT  
WEDNESDAY AFTERNOON. PERIODS OF UNSETTLED WEATHER CONTINUE LATE  
THIS WEEK INTO THIS WEEKEND...BUT NOT EXPECTING A WASHOUT  
EITHER WITH EXTENDED PERIODS OF DRY WEATHER TOO.  
OVERALL...TEMPERATURES WILL AVERAGE BELOW NORMAL LATE THIS WEEK  
INTO THE WEEKEND. MILDER/SEASONABLE TEMPERATURES SHOULD RETURN  
EARLY NEXT WEEK.  
 

 
   
NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/
 
 
950 PM UPDATE...  
 
STRATUS AND FOG CONFINED TO CAPE/ISLANDS TONIGHT, AND AS  
PREVIOUS FORECASTER INDICATED WILL NOT LIKELY PUSH MUCH FURTHER  
N THAN THE SOUTH COAST GIVEN THE WSW BL FLOW. NO CHANGE IN  
TIMING OF WARM FRONTAL SHOWERS WHICH WILL BEGIN TO MOVE INTO  
WESTERN MA/CT TOWARD DAYBREAK AND OVERSPREAD REST OF SNE AFTER  
DAYBREAK.  
 
PREVIOUS DISCUSSION...  
 
* AREAS OF LOW CLOUDS/FOG EXPAND ONTO THE SOUTH COAST OVERNIGHT  
* SHOWERS/EMBEDDED T-STORMS APPROACH WESTERN MA/CT NEAR  
DAYBREAK  
 
AREAS OF LOW CLOUDS AND FOG WERE CURRENTLY IMPACTING NANTUCKET  
EARLY THIS EVENING. LIGHT SOUTHERLY FLOW WITH THE COOLING  
BOUNDARY LAYER SHOULD ALLOW THE LOW CLOUDS AND FOG TO  
OVERSPREAD AREAS NEAR THE SOUTH COAST OVERNIGHT. THE LOW LEVEL  
FLOW WILL MAINTAIN A WESTERLY COMPONENT OVERNIGHT...WHICH SHOULD  
KEEP THE BULK OF THE LOW CLOUDS/FOG FROM EXPANDING MUCH FURTHER  
NORTH THAN A KPVD-KPYM LINE.  
 
THE OTHER CONCERN WILL BE SHORTWAVE ENERGY/MID LEVEL WARM FRONT  
APPROACHING FROM THE WEST NEAR DAYBREAK WEDNESDAY. THIS WILL BE  
ASSOCIATED WITH A MODEST SOUTHWEST LLJ AND A PRETTY GOOD  
INSTABILITY BURST. SHOWALTER INDICES DROP FROM NEARLY 10 TO  
BELOW ZERO WEDNESDAY MORNING. THERE ALSO A BAND OF GOOD  
LIFT/DEEPER MOISTURE ASSOCIATED WITH THE SHORTWAVE/MID LEVEL  
WARM FRONT. THEREFORE...WHILE DRY WEATHER GENERALLY PREVAILS  
OVERNIGHT EXPECT SHOWERS AND POSSIBLY EMBEDDED T-STORMS WITH  
BRIEF HEAVY RAIN TO BEGIN TO IMPACT WESTERN MA/CT NEAR DAYBREAK.  
THIS ACTIVITY WILL THEN MOVE ACROSS THE REGION WEDNESDAY  
MORNING WHICH IS DISCUSSED IN THE SHORT TERM SECTION.  
 
OVERNIGHT LOW TEMPS WILL BOTTOM OUT IN THE UPPER 40S TO THE  
MIDDLE 50S.  
 

 
   
SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/
 
 
350 PM UPDATE:  
 
WEDNESDAY:  
 
KEY POINTS...  
 
* OVERCAST WITH WARM FRONTAL SHOWERS SPREADING EASTWARD DURING THE  
MORNING TO EARLY AFTERNOON HRS. LOW CHANCE OF A RUMBLE OF THUNDER  
WITH THIS ACTIVITY.  
 
* BETTER CHANCE AT A FEW STRONG T-STORMS LATER IN AFTERNOON (AS  
SOON AS 2 PM, BUT MORE PROBABLE ~ 4-7 PM) FROM WORCESTER/NW  
RI WESTWARD INTO WESTERN MA/CT. HAIL POSSIBLE IN THE STRONGEST  
OF STORMS, WHICH COULD REACH UP TO 1 INCH IN DIAMETER.  
 
WARM FRONT THEN SPREADS SHOWERS EASTWARD ACROSS THE REMAINDER OF  
SOUTHERN NEW ENGLAND DURING THE MORNING HOURS, WITH  
CONTINUING/RESIDUAL SHOWERS AROUND IN EASTERN MA INTO THE EARLY  
AFTERNOON. THERE IS A MODEST DECREASE IN SHOWALTER INDICES TO AROUND  
0 WITH THIS MORNING ROUND OF SHOWERS, AND THOUGH I CAN'T RULE OUT A  
RUMBLE OF THUNDER WITH THE MORNING WARM FRONTAL SHOWERS, IN MANY  
CASES IT WOULD BE THE EXCEPTION VS THE RULE. THIS WILL LOCK IN CLOUD  
COVER AND LEAD TO COOLER TEMPERATURES WITH LITTLE OPTIMISM FOR  
BREAKS IN THE CLOUD COVER. WITH OVERCAST HERE, EXPECT HIGHS TO REACH  
INTO THE MID 50S TO LOWER/MID 60S.  
 
FOR THE MID TO LATE AFTERNOON...THERE ARE INDICATIONS IN A MAJORITY  
OF GUIDANCE OF SOME BREAKS IN THE CLOUD COVER OVER WESTERN AND  
CENTRAL MA, NORTHERN CT AND INTO PORTIONS OF NW RI. AS THAT OCCURS,  
A SURGE IN 700-500 MB LAPSE RATES 7.0-7.5 C/KM ADVECTS OVER THE  
AFOREMENTIONED AREA, WITH A POCKET OF MID 50S TO AROUND 60 DEGREE  
DEWPOINTS IN THE LOWER HUDSON VALLEY INTO WESTERN MA AND PORTIONS OF  
NORTHERN CT. WITH EFFECTIVE SHEAR MAGNITUDES AROUND 40-50 KT, AND  
WITH A NARROW ZONE OF FRONTAL CONVERGENCE WITH WEAK LOW PRESSURE  
TRACKING UP THE CT VALLEY, WE SHOULD SEE SCATTERED T-STORMS DEVELOP  
IN THE LOWER HUDSON VALLEY/BERKSHIRES, MOVING ESE DURING THE LATE-  
AFTN HOURS. MUCAPE VALUES FOR THE AFOREMENTIONED AREA ARE  
PROGGED AROUND 1000-1200 J/KG PER THE HREF, WITH A BULLSEYE IN  
MAX UPDRAFT PROGS OVER WESTERN AND CENTRAL MA, NORTHERN CT INTO  
NORTHWEST RI. IT ISN'T CLEAR IF THESE STORMS WOULD BE SURFACE-  
BASED HERE, BUT THE STEEPER LAPSE RATES ALOFT COMBINED WITH  
EFFECTIVE SHEAR MAGNITUDES SUPPORTING ORGANIZED UPDRAFTS COULD  
FAVOR STORMS ELEVATED ABOVE ANY SURFACE STABLE LAYER/INVERSION.  
IT'S A SETTING WHICH CAN YIELD STORMS CAPABLE OF HAIL IN STRONG  
STORMS, AND PER MACHINE- LEARNING PROGS FROM COLORADO STATE AND  
OTHERS, THERE IS A LOWER PROBABILITY THAT STORMS COULD PRODUCE  
HAIL SATISFYING SEVERE CRITERIA. SPC HAS A LARGE PORTION OF SNE  
IN A LEVEL 1 OF 5/MARGINAL RISK FOR SEVERE WEATHER, THOUGH THE  
BEST CHANCE IS FOR AREAS NEAR AND SOUTHWEST OF WORCESTER. UNLESS  
STORMS CAN BECOME SURFACE BASED, THE PRIMARY CONVECTIVE THREAT  
WOULD BE FROM HAILSTONES. OPTED TO INCLUDE ENHANCED WORDING FOR  
SMALL HAIL IN THUNDERSTORMS ENCOMPASSING THIS GENERAL AREA. THE  
BIGGEST UNCERTAINTIES HERE ARE ON THE SPATIAL COVERAGE AND  
TIMING OF ANY T- STORMS, AND IF STORMS COULD BECOME SURFACE-  
BASED. TEMPS IN INTERIOR MA/CT AND NORTHWEST RI HAVE A GOOD  
CHANCE AT REACHING INTO THE MID 60S TO LOWER 70S WITH ANY CLOUDY  
BREAKS.  
 
WEDNESDAY NIGHT:  
 
WEAK LOW PRESSURE INITIALLY NEAR THE HUDSON VALLEY MOVES EASTWARD  
EARLY TOMORROW NIGHT, WITH DECREASING RAIN CHANCES AS IT MOVES  
OFFSHORE. IT'S A PRETTY UNCERTAIN PERIOD THOUGH IN THE WAKE OF THIS  
WAVE OF LOW PRESSURE; A NUMBER OF MODEL GUIDANCE WANTS TO CLEAR SNE  
OUT FROM CLOUD COVER TOO, BUT WITH SURFACE RIDGE NOSING IN FROM  
NORTHERN NEW ENGLAND AND LIGHT NORTHERLY WINDS COOLING THE PBL, I'M  
A LITTLE SURPRISED THE GUIDANCE IS CLEARING THINGS OUT TO THE DEGREE  
IT IS. PATTERN RECOGNITION SEEMS TO FAVOR MORE CLOUD COVER THAN  
THE GUIDANCE IS OFFERING. I SIDED THE OFFICIAL FORECAST MORE  
PESSIMISTICALLY, WITH CLOUD COVER HANGING TOUGH AND/OR FILLING  
BACK IN AS THE PBL COOLS OFF. WILL BE GENERALLY DRY, BUT I THINK  
TOMORROW NIGHT COULD FEATURE A GOOD AMT OF CLOUD COVER AND  
POSSIBLE FOG, TOO. LOWS IN THE UPPER 40S TO LOWER 50S.  
 

 
   
LONG TERM /THURSDAY THROUGH TUESDAY/
 
 
KEY POINTS...  
 
* ANOTHER PERIOD OF SHOWERS SOMETIME LATER THU INTO EARLY FRI  
* SEASONABLE HIGH TEMPS AWAY FROM COAST THU BUT QUITE COOL ON FRI  
* RELATIVELY COOL THIS WEEKEND WITH ANOTHER PERIOD OF SHOWERS BY SUN  
* MILDER/MORE SEASONABLE TEMPS RETURN EARLY NEXT WEEK  
 
DETAILS...  
 
THURSDAY AND THURSDAY NIGHT...  
 
ENOUGH SUBSIDENCE BEHIND WEDNESDAY/S SHORTWAVE TO RESULT IN MAINLY  
DRY WEATHER TO START OFF THE DAY ON THURSDAY. HOWEVER...ANOTHER  
PIECE OF SHORTWAVE ENERGY WILL BE APPROACHING FROM THE WEST LATER  
THU AND THU NIGHT. SO WE EXPECT MORE SHOWERS TO ARRIVE...BUT  
SPECIFIC TIMING IS UNCERTAIN. RIGHT NOW THINKING LATER THU INTO THU  
NIGHT...BUT THIS WILL NEED TO BE REFINED. HIGH TEMPS ARE TRICKY  
TOO...BUT WE MIGHT HAVE ENOUGH OF A DRY WINDOW DURING THE FIRST HALF  
OF THE DAY TO ALLOW HIGHS TO REACH THE 60S TO PERHAPS NEAR 70 IN CT  
RIVER VALLEY. IT PROBABLY WILL BE TOUGH THOUGH TO BREAK 60 IN THE  
IMMEDIATE COAST WITH ONSHORE FLOW.  
 
FRIDAY...  
 
A COUPLE WAVES OF LOW PRESSURE PASS TO OUR SOUTH ON FRIDAY. THIS  
GENERATES AN EASTERLY FLOW OF COOL AIR INTO SOUTHERN NEW ENGLAND.  
HIGH TEMPS WILL PROBABLY BE HELD MAINLY IN THE 50S ON FRIDAY.  
THINKING THE MAIN SHOWER THREAT WILL BE DURING THE FIRST PART OF THE  
DAY, BUT PERHAPS TRENDING DRIER FOR THE SECOND HALF OF THE DAY AS  
THE LOW PRESSURE SYSTEM MOVES EAST OF THE REGION.  
 
THIS WEEKEND...  
 
UPPER TROUGH SETS UP ACROSS OUR REGION THIS WEEKEND. THIS WILL  
RESULT IN RELATIVELY COOL/BELOW NORMAL HIGH TEMPS FOR MOST OF THE  
WEEKEND ALONG WITH ONSHORE FLOW. THINKING IS THAT HIGHS WILL MAINLY  
BE BETWEEN 55 AND 65...WITH THE COOLEST OF THOSE READINGS ON THE  
IMMEDIATE COAST. IT WILL ALSO BE A BIT UNSETTLED AT TIMES WITH THE  
RISK FOR SOME SHOWERS...BUT TIMING IS UNCERTAIN AND A WASHOUT IS NOT  
EXPECTED. CURRENT INDICATIONS ARE THAT MUCH OF SAT MAY TURN OUT DRY  
WITH THE BETTER CHANCE FOR SOME SHOWERS BEING SOMETIME ON SUN.  
 
EARLY NEXT WEEK...  
 
THE UPPER TROUGH WILL PUSH EAST OF OUR REGION EARLY NEXT WEEK. THIS  
SHOULD ALLOW FOR RISING HEIGHT FIELDS AND SEASONABLE HIGH  
TEMPERATURES.  
 

 
   
AVIATION /02Z WEDNESDAY THROUGH SUNDAY/
 
 
FORECAST CONFIDENCE LEVELS:  
 
LOW - LESS THAN 30 PERCENT.  
MODERATE - 30 TO 60 PERCENT.  
HIGH - GREATER THAN 60 PERCENT.  
 
00Z TAF UPDATE...  
 
TONIGHT...HIGH CONFIDENCE FOR MOST OF THE REGION BUT MODERATE  
CONFIDENCE NEAR THE SOUTH COAST.  
 
WE GENERALLY EXPECT VFR CONDITIONS TO PREVAIL FOR MOST AREAS  
TONIGHT. THE EXCEPTION WILL BE AREAS NEAR THE SOUTH COAST, CAPE  
AND ISLANDS...WHERE IFR-LIFR CONDITIONS IN LOW CLOUDS AND FOG  
ARE EXPECTED TO OVERSPREAD THE REGION. THIS AS THE BOUNDARY  
LAYER BEGINS TO COOL WITH LIGHT SOUTHERLY FLOW. WE DO NOT EXPECT  
THESE LOW CLOUDS/FOG TO ADVANCE MUCH FURTHER NORTH THAN THE  
PVD-PYM CORRIDOR GIVEN A WESTERLY COMPONENT TO THE WIND.  
 
WEDNESDAY...MODERATE CONFIDENCE.  
 
LOW END MVFR-IFR CONDITIONS WILL TEND TO OVERSPREAD THE  
REMAINDER OF THE REGION WED MORNING. THIS WILL ALSO BE  
ASSOCIATED WITH A CLUSTER OF SHOWERS AND POSSIBLY EMBEDDED  
T-STORMS IMPACT THE REGION ROUGHLY IN THE 10Z TO 16Z TIME FRAME.  
TIMING IS TOUGH AND AREAL COVERAGE/CONFIDENCE IN THUNDER  
REMAINS SOMEWHAT UNCERTAIN. SO WE DID INCLUDE PROB30 GROUPS FOR  
THUNDER AT MOST TERMINALS AND BRIEF HEAVY RAIN IS ALSO POSSIBLE  
WITH THE ACTIVITY. A SECOND ROUND OF SCATTERED SHOWERS/T-STORMS  
IS POSSIBLE LATER IN THE DAY AND EARLY EVENING. FOR NOW WE DID  
INCLUDE SOME VCTS IN BDL/BAF/ORH TAFS AND LATER SHIFTS MAY NEED  
TO EXPAND ON THAT DEPENDING ON MODEL TRENDS. SOME HAIL IS  
CERTAINLY POSSIBLE TOO WITH THE AFTERNOON/EARLY EVENING  
ACTIVITY.  
 
WEDNESDAY NIGHT: LOW TO MODERATE CONFIDENCE.  
 
SHRA/TS EXITS INTO THE WATERS EARLY WED NIGHT, AND THAT COULD  
LEAD TO A PERIOD OF CLEARING/BRIEF VFR. HOWEVER THERE'S  
POTENTIAL FOR IFR TO RE-DEVELOP LATER IN THE OVERNIGHT INTO  
THURS AS HIGH PRESSURE RIDGES SOUTHWARD FROM ME/NH. LIGHT WINDS  
TO TREND LIGHT NE BY OVERNIGHT.  
 
KBOS TAF...HIGH CONFIDENCE IN TAF TONIGHT AND MODERATE  
CONFIDENCE ON WEDNESDAY.  
 
KBDL TAF...HIGH CONFIDENCE IN TAF TONIGHT AND MODERATE  
CONFIDENCE ON WEDNESDAY.  
 
OUTLOOK /THURSDAY THROUGH SUNDAY/...  
 
THURSDAY: MAINLY VFR, WITH LOCAL IFR POSSIBLE. BREEZY. CHANCE  
SHRA, PATCHY FG.  
 
THURSDAY NIGHT: MVFR/IFR CONDITIONS POSSIBLE. BREEZY. SHRA  
LIKELY, PATCHY BR.  
 
FRIDAY: MAINLY MVFR, WITH AREAS IFR POSSIBLE. BREEZY. CHANCE  
SHRA.  
 
FRIDAY NIGHT: MAINLY MVFR, WITH LOCAL IFR POSSIBLE. BREEZY.  
CHANCE SHRA.  
 
SATURDAY: MAINLY MVFR, WITH LOCAL VFR POSSIBLE. BREEZY. CHANCE  
SHRA.  
 
SATURDAY NIGHT: MAINLY MVFR, WITH AREAS VFR POSSIBLE. BREEZY.  
SLIGHT CHANCE SHRA.  
 
SUNDAY: MAINLY MVFR, WITH AREAS VFR POSSIBLE. CHANCE SHRA.  
 

 
   
MARINE
 
 
FORECASTER CONFIDENCE LEVELS:  
 
LOW - LESS THAN 30 PERCENT.  
MEDIUM - 30 TO 60 PERCENT.  
HIGH - GREATER THAN 60 PERCENT.  
 
THROUGH WEDNESDAY NIGHT: HIGH CONFIDENCE.  
 
WINDS AND SEAS BELOW SCA THRESHOLDS THROUGH THE PERIOD.  
 
MAINLY EASTERLY WINDS AROUND 10-15 KT TONIGHT INTO WEDNESDAY;  
WINDS THEN TURN WNW TO NW AT SIMILAR SPEEDS FOR WEDNESDAY NIGHT.  
SEAS MAINLY 4 FT OR LESS ALL WATERS. FOG IS LIKELY TONIGHT OVER  
THE SOUTHERN WATERS. PERIODS OF SHOWERS WEDNESDAY, WITH  
POSSIBLE EMBEDDED THUNDERSTORMS. SOME STORMS COULD PRODUCE SMALL  
HAIL AND LOCALLY ROUGH SEAS.  
 
OUTLOOK /THURSDAY THROUGH SUNDAY/...  
 
THURSDAY: WINDS LESS THAN 25 KT. CHANCE OF RAIN SHOWERS, PATCHY  
FOG. LOCAL VISIBILITY 1 NM OR LESS.  
 
THURSDAY NIGHT: LOW RISK FOR SMALL CRAFT ADVISORY WINDS WITH  
GUSTS UP TO 25 KT. AREAS OF SEAS APPROACHING 5 FT. RAIN SHOWERS  
LIKELY, PATCHY FOG. LOCAL VISIBILITY 1 TO 3 NM.  
 
FRIDAY: MODERATE RISK FOR SMALL CRAFT ADVISORY WINDS WITH GUSTS  
UP TO 30 KT. SEAS UP TO 5 FT. CHANCE OF RAIN SHOWERS.  
 
FRIDAY NIGHT THROUGH SATURDAY: WINDS LESS THAN 25 KT. SEAS UP  
TO 5 FT. CHANCE OF RAIN SHOWERS.  
 
SATURDAY NIGHT: WINDS LESS THAN 25 KT. SEAS UP TO 5 FT. SLIGHT  
CHANCE OF RAIN SHOWERS.  
 
SUNDAY: WINDS LESS THAN 25 KT. AREAS OF SEAS APPROACHING 5 FT.  
CHANCE OF RAIN SHOWERS.  
 

 
   
TIDES/COASTAL FLOODING
 
 
950 PM UPDATE...  
 
WE ISSUED A COASTAL FLOOD STATEMENT FOR THE UPCOMING HIGH TIDE  
AS A NEAR 1 FT SURGE MAY LEAD TO POCKETS OF SPLASHOVER GIVEN  
HIGH ASTRONOMICAL TIDES.  
 
PREVIOUS DISCUSSION...  
 
HIGH ASTRONOMICAL TIDES COUPLED WITH ONSHORE FLOW MAY RESULT IN  
SOME SPLASHOVER/VERY MINOR COASTAL FLOODING LATE THIS WEEK.  
HOWEVER...WIND/WAVES DO NOT APPEAR HIGH ENOUGH TO RESULT IN A  
SIGNIFICANT ISSUES.  
 

 
   
BOX WATCHES/WARNINGS/ADVISORIES
 
 
CT...NONE.  
MA...NONE.  
RI...NONE.  
MARINE...NONE.  
 

 
 

 
 
SYNOPSIS...FRANK/LOCONTO  
NEAR TERM...KJC/FRANK  
SHORT TERM...LOCONTO  
LONG TERM...FRANK  
AVIATION...FRANK/LOCONTO  
MARINE...FRANK/LOCONTO  
TIDES/COASTAL FLOODING...FRANK  
 
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